van Veldhuizen M J, Feenstra M G, Boer G J
Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research.
Brain Res. 1994 Jan 28;635(1-2):238-48. doi: 10.1016/0006-8993(94)91445-1.
Microdialysis was used to determine extracellular levels of both noradrenaline and its metabolites in several brain regions of rats under basal conditions and in response to drugs selective for the alpha 2-adrenoceptor to study regional differences in the regulation of noradrenaline overflow. Basal overflow of noradrenaline was about 1.3 fmol/min in frontoparietal cortex, amygdala and hippocampus and in the medial prefrontal cortex 2.4 fmol/min was measured, whereas the overflow of the noradrenaline metabolites 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol was 10-fold higher. After correction for recovery and membrane length no regional differences in the basal overflow of noradrenaline (NA) were found. There were, however, regional differences in the drug-induced effects: locally applied moxonidine decreased extracellular noradrenaline stronger in the frontoparietal cortex than in the medial prefrontal cortex. The increase in noradrenaline overflow caused by idazoxan (10(-4) M) was stronger in frontoparietal cortex than in amygdala and hippocampus. The metabolites were also generally decreased by moxonidine and increased by idazoxan, although less markedly. The present study shows that the regulation of noradrenaline overflow by the presynaptic alpha 2-autoreceptor was stronger in cortical regions than in amygdala and hippocampus. In those latter regions the uptake mechanism probably plays a relatively more important role in the regulation of noradrenaline overflow.
采用微透析技术测定大鼠基础状态下以及给予α2 -肾上腺素能受体选择性药物后，几个脑区细胞外去甲肾上腺素及其代谢产物的水平，以研究去甲肾上腺素溢出调节的区域差异。在额顶叶皮质、杏仁核和海马中，去甲肾上腺素的基础溢出量约为1.3 fmol/分钟，在内侧前额叶皮质测得的溢出量为2.4 fmol/分钟，而去甲肾上腺素代谢产物3,4 -二羟基苯乙二醇和3 -甲氧基-4 -羟基苯乙二醇的溢出量则高10倍。校正回收率和膜长度后，未发现去甲肾上腺素（NA）基础溢出存在区域差异。然而，药物诱导效应存在区域差异：局部应用莫索尼定使额顶叶皮质细胞外去甲肾上腺素降低的程度比内侧前额叶皮质更强。咪唑克生（10(-4) M）引起的去甲肾上腺素溢出增加在额顶叶皮质比在杏仁核和海马中更明显。莫索尼定通常也会使代谢产物减少，而咪唑克生则使其增加，尽管不太明显。本研究表明，突触前α2 -自身受体对去甲肾上腺素溢出的调节在皮质区域比在杏仁核和海马中更强。在后者区域，摄取机制可能在去甲肾上腺素溢出的调节中发挥相对更重要的作用。
